Rotary treater for ores



P 1950 B. BURWELL Q 2,521,896

ROTARY TREATER FOR ORES Original Filed Jan. 1, 1942 2 Sheets-Sheet 1 R E DIGESTANT DIGESTER DIGESTER CONDENSER CONDENSER 1 I FILTER FILTER PARTLY 1 DIGESTED oRE FILTRATE' FILTRATE CONTAINING GANGUE TO BE ORE VALUES DISCARDED INVENTOR Sept. 12, 1950 B. BURWELL ROTARY TREATER FOR ORES Original Filed Jam. 1,, 1942 VII ' UIIIIIIIIII INVENTOR BLAIR BURWELL ATTORNEY Patented Sept. 12, 1950 Y ration of Delaware- January 1, 1942. Thi 1346, Serial No. 702,451

- 4 Claims. (01. 23- -269.)

The invention relates to the treatment of ores to recover-i valuable material therefrom and refers more particularlyfto method of ore treatment whichfinv'olve' digestion of the ore with a solvent or''i'eajctant' and "to apparatus for treating ores. me-sue the invention is applicable in general tothe 'treat i nentof any ores of the type which mustbe chemically digested, for conciseness it it wllbe described'fwith' particular'reference to tungstenoresfsuch as'scheelite'. r

iT T'he're Xisti'n, this'country large deposits of scheelit'e; but the ore contains many impurities and is generauy'or a low grade. Moreover, the ore is of the type that is not amenable to efiicient mechanical separation 'of tungsten from gangue. For nstance; the recovery of'tungsten from it mechanicalrnethods of concentration has been aslowtas Chemical methods of separating tungsten ii-em,.worthlessmaterials in sche'elite,

including digestion dfthe forewith sodium carbon'ate at superatmlosphric pressure and elevated temperature,have been proposed, but such methods have been conducted only as small scale, batch-jtype operations. 'fBatch' operations are wasteful of time and money, and'thecost'of the tune enp ocl e .h be i A a consequence of these difiiculties, domestic scheelite has beenonly a minorsource of supply of the. tungsten used inthis country, chief reliance, for tungsten having been placed on foreign sources. Improvement is therefore sought. in methods of .treatingdomestic. ores to recover tungsten efliciently,and economioallys I It is an important object of this invention to provide improvement in the chemical treatment of ores to. recover valuable materials therefrom in an efficient manner. A more particular object is improvement in the digestion of tungsten ores suchas scheelite whereby such digestion may be conducted in a continuous manner. A further objectis the provision of apparatusfor use in the chemical treatment ofores.

The invention .by means of which these objects are achieved will be described with reference to the accompanying drawing in which:

- Fig. 1 is a flow diagram of a continuous digestion system;

Figs. 2 and 20, together are a side elevation of a dige'ster vessel and connected condenser for use in the digestion system shown in Fig. '1, parts being broken away to show details of construction;

Fig. 3 is an enlarged sectional View of the feeding m ans F shown in Fig. 2;

2,521,896 ROTARY TREATER FOR ones Blair Burw'ell, Grand Junction, 0010., assignor to United States VanadiumCorporation, a'corpo- Continuation of application. Serial No. 425,367, s application October. 10,

Fig. 4 is an enlarged view, partly in section; of the discharge piping shown in Fig. 2d; Fig. 5 is asectional view of a part of -the dis charging means R shown in Fig. 2d; and

Fig. 6 is a sectional view taken along theline BS of Fig; 5 looking in the direction ot" the arrows. x L Inaccordance' with the invention, the digestion of an ore material is conducte'd as indicated by the flow diagram; Fig. 1 of thedrawing, ina plurality of stages, indigester'vesselspreferably of the improved construction to be described hereinafter in detail. In one stage, into a digester vessel there-is continuously fed a slurry consist? ing of fresh digestant and-of partiallyfl'digested residue ore material which has been removed from another digester vessel at another-stage. In anotherstage, the filtrate liquor from theiir'st mentioned digester vessel is mixed with "com rninuted; fresh, undigested ore" material to form a slurry which is then fed intofa second-digester vessel. The undissolved material" from the-*s'ec ond-mentioned digester vessel is inii redwi thfresh digestant to-form a 'slurryand isthenreturned to the first-mentioned digester vessel. The tern perature of the slurry inside of each "digester vesselisraised to above the boiling'point of'the digestant, whereby to raise the pressureins'ide the vessel. Preferably this is accomplished by injectingsteam at superatmosphericpressure "into the vessel in admixture with'the;slurry. *The slurry is digested for a time sumcient to allow the desired reaction to be substantially complete'd, and is then removed from the digester vessel, passed'through the cooling coils of a con denser in heat exchange relationship with 'acool ing medium to cool it to a temperature below the boilingpoint of the digestant, thereby'to re-- duce the pressure, for example', to atmospheric pressure, and filtered. The undissolved material from the first-mentioned stage, Which'cons'ists mostly of gangue, may be discarded or may be mixed with digestant to form a new slurry and redigested. The filtrate from the second-mentioned digester, containing the desired metal, i delivered to a metal-recovery process inwhich the valuable metal may here-- covered inknown manner.

From this description of the digester system andfrom a study of the flow sheet illustrated in Fig. 1 of the drawing it willbe evidenttha't the invention provides a continuous method of digest-- ingore material to separate valuable-metal from gangu'e. However, to achieve continuous operation of. this system, itis necessary thatsnecial digester D is an elongated, generally cylindrical I vessel mounted horizontally and is provided with end caps I0, II. The vessel D is rotatable about its longitudinal axis and is rotated by a train of gears I2, I3, driven by a motor I4. Idler gears I5, I6, may be provided for stability. The digester vessel D is provided with continuous feeding means F and continuous discharge means R.1

The continuous feeding means F comprises an axially located inlet pipe I1 through which the slurry of ore and digestant may be admitted axially into one end of the digester D from a supply pipe I8. A tubular shaft I9 which passes through the cap ID of the digester D and a collar. joined thereto is journalled in a packing gland 2I so that the shaft I9 will rotate with the digester D. The gland 2I is provided with packing 22 in sealing contact with the tubular shaft [9, and a gland nut 23 is provided to compress the packing 22. Steam may be, admitted axially into one end of the digester D through the annu- Iar space 24 formed between the tubular shaft I3 andthe slurry inlet pipe I1 from a supply pipe 25 joined to the gland 2|.

The slurry inlet pipe I1 and the annular space communicate with a T-shaped bafile 26 located within .the digester D and provided with a closed e nd..21-and an open end 28. The baflie 26 is mounted on atubular shaft 29 which is secured toa collar 30 secured to the cap II] of the digester vesselD. Thus, the baflie 26 willrotate with the digester-ves's el D. I V V To permit the continuous removal of digested material axially from the other end of the digesterD, .the digester is provided with continuous discharging means R, illustrated in detail in Figs. 5- and 6, comprising a spiral scoop 'pipe 3! mounted within the end cap II of the digester vessel-D. The scoop pipe 3| is provided with an mounted on the inside of the cap II and on a perforated plate 34 provided in the digester ves sel- D, the scoop pipe 3I being located between the perforated plate 34 and the end-cap l I. This mounting of the scoop pipe 3| permits it to, rotate with the digester vessel D and the open end 32, being located adjacent to the inner cylindrical surface of the vessel D, and extending in the direction of rotation of the latter, will scoop hot slurry into the pipe 3| and discharge such slurry through the outlet pipe 33 as the vessel rotates. The discharge pipe 33 is joined to the cap II v and communicates with an opening 35 therein and with an external discharge pipe 36 provided with a-valve-31. The discharge side of the valve 31 is connected by suitable piping including a flanged joint 38 and a flexible coupling 39 to a second valve 40, the flexible coupling 39 being used to provide flexibility in the discharge pipingand the joint 38 being inserted to providefor dismantling the piping for repairs if necessary.

4 A pipe 4! from the discharge side of the valve 40 is journalled in a gland 42 provided with packing 43 in sealing contact with the discharge pipe 4I. The gland 42 is provided with a nut 44 for compressing the packing 43. Suitable stationary piping 45, having a part coaxial with and communicating with the rotating pipe 4! may be connected to a flange of the gland 42 for delivery of the hot digested material to a condenser C.

The condenser C, illustrated in Fig. 2a of the drawing, comprises a tank 46 having a slurry inlet pipe 41 which is connected to the gland 42 by suitable piping thereby providing for the delivery of digested material from the vessel D to the condenser C. The slurry inlet pipe 41 leads to an elongated stationary pipe or cooling .coil 48 in the tank 46 provided with an outlet 49. Cooling water is circulated through the tank 46 through an inlet 50 and an outlet 5I. The cooling water may be agitated by an agitator 52 driven by a motor 53.

In operation, the digester D is rotated by the motor I4 acting through the gears I2, I3. A slurry of ore material and digestant is fed through the slurr yinlet pipe ll from the slurry supply pipe I8 while steam is admitted fromthe steam supply pipe 25 through the annular space 24; The steam and slurry are delivered into the rotating bafiie 26 and through its open end 28 to the interior of the digester D. By this method of delivery all of the slurry is delivered so that it will pass through the digester D in a predetermined path of travel at a rate dependent onthe rotation of the digester;

Rotation of the digester D causes the slurry to move through the digester and to be delivered through the perforated plate 34 which effectively bars the passage of large lumpsof material to the end cap II. The scoop pipe 3| rotates with the digester D', and its open end 32 scoops digested material from theend cap II, discharging it through the pipe 33.

The digested material removed from "the digesterD is delivered through the discharge piping and the'slurry inlet 41 to the coo1ingcoil 48 of the condenser C. As the slurry passes through the cooling coil 33, it is cooled to a temperature below C., and the steam present is condensed. Passage of the slurry through the coil- 48 and the consequent cooling of the slurry to below its boiling point cause the pressure to be reduced so that the slurry may be dischargedat atmospheric pressure through the outlet pipe 49 to the'next step in theprocess, filtration.

' The apparatus of the invention makes possible the emcient and economical separation of .valIuabie metals from ores. It is particularly advantageous in providing for the continuous treatment of ores; large quantities of ore may be digested at low cost compared with the cost of batch treatment The recycling of partially digested ore increases the efllciency of separation, .making possible the recovery of a high percentageof the valuable metal from the ore, and also-leads to the production of a purer product than can be obtained by mechanical separation methods. -The invention thus provides. an apparatus for treating low grade ores, such as domestic scheelite, to recover valuable metals therefrom at low cost, and thereby, particularly in the case oftungsten, provides for an increased domestic supply of valuable metal.

It has been found that the digestion of scheelite using the. apparatus and method of the invention is most efficiently carried out at'a temperae ture above about 125 0., preferably in the neighborhood of 200 C. using as a digestant an alkaline material, for example, an aqueous solution of sodium carbonate. Under these conditions, recoveries of tungsten as high as 96% to 100% have been obtained.

Although the invention has been described with particular reference to the treatment of tungsten ores, it is applicable to the treatment of any ores of the type which are treated by chemical methods involving digestion. And although specific details of construction of the apparatus forming one embodiment of the invention have been given, modifications therein will be apparent. Such modifications are within the scope of the invention.

This application is a continuation of my application Serial No. 425,367, filed January 1, 1942, now forfeited.

What is claimed is:

1. In a digester for treating a slurry of comminuted ore material and aqueous digestant, the combination of an elongated, substantially horizontal, generally cylindrical vessel mounted for rotation about its longitudinal axis; mechanism for rotating said vessel about said axis; means for feeding such slurry into one end of said vessel while the latter is rotating; means for applying heat to the slurry within said vessel while the latter is rotating; and means constructed and arranged to discharge hot slurry from the other end of said vessel while the latter is rotate-d by said mechanism, such discharging means comprising a pipe rotatable with said vessel and located within said vessel adjacent the other end thereof, said pipe having its inlet end located adjacent the inner cylindrical surface of said vessel and extending in the direction of rotation of said vessel so as to scoop hot slurry into said pipe as said vessel rotates, said pipe having its outlet located at the longitudinal axis of said vessel.

2. In a digester for treating a slurry of comminuted ore material and aqueous digestant, the combination of an elongated, substantially horizontal. generally cylindrical vessel mounted for rotation about its longitudinal axis; mechanism for rotating said vessel about said axis; means constructed and arranged to feed both slurry and steam into one end of said vessel while the latter is rotated by said mechanism; and means constructed and arranged to discharge hot slurry from the other end of said vessel while the latter is rotated by said mechanism, such discharging means comprising a substantially helical pipe rotatable with said vessel and located therein adjacent the other end thereof, said pipe having its inlet end located adjacent the inner cylindrical surface of said vessel and extending in the direction of rotation of said vessel so as to scoop hot slurry into said pipe as said vessel rotates, said pipe having its outlet located at the longitudinal axis f said vessel.

3. In apparatus for treating a slurry of cominuted ore material and aqueous disgestant, the

combination of an elongated, substantially horizontal, generally cylindrical, closed vessel mounted for rotation about its longitudinal axis and built to withstand high swam pressures; means for rotating said vessel about said axis; axially located inlet means extending into one end of said vessel for feeding slurry thereinto while said vessel is rotating; means for applying heat to said slurry within said vessel while the latter is rotating; a pipe extending from within the other end of said vessel outwardly and axially therethrough for discharging hot slurry from said r0- tating vessel; and a conduit outside said vessel and communicating with said pipe to receive hot slurry discharged from the latter while the vessel is rotating, said conduit being of such length that said slurry will be discharged therefrom at substantially atmospheric pressure when cooling water is applied to said conduit; and means associated with said conduit for applying cooling water to the latter.

4. In apparatus for treating a slurry of ore material and a digestant, the combination of an elongated, substantially horizontal, generally cylindrical vessel mounted for rotation about its horizontal axis; mechanism for rotating said vessel about said axis; means for feeding such slurry axially into one end of said vessel while the latter is rotating; means for applying heat to the slurry within said vessel while the latter is rotating; a conduit pipe rotatable with and extending within and axially from the other end of said vessel, the inner end of said pipe being so arranged and constructed off the axial line that hot slurry is discharged therethrough while the vessel is rotating; a stationary cooling coil outside said vessel and comprising a stationary pipe having a part thereof coaxial with and communicating with said rotatable pipe to receive the hot slurry discharged by the latter while said vessel and rotatable pipe are rotated; and means associated with said cooling coil for applying cooling water to the latter to cool the hot slurry flowing therethrough.

BLAIR, BURWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,301,360 Bender Apr. 22, 1919 1,308,576 Calvert et al July 1, 1919 1,424,335 Bodman Aug. 1, 1922 1,485,507 Juer Mar. 4, 1924 1,799,256 Satow Apr. 7, 1931 

1. IN A DIGESTER FOR TREATING A SLURRY OF COMMINUTED ORE MATERIAL AND AQUEOUS DIGESTANT, THE COMBINATION OF AN ELONGATED, SUBSTANTIALLY HORIZONTAL, GENERALLY CYLINDRICAL VESSEL MOUNTED FOR ROTATION ABOUT ITS LONGITUDIAL AXIS; MECHANISM FOR ROTATING SAID VESSEL ABOUT SAID AXIS; MEANS FOR FEEDING SUCH SLURRY INTO ONE END OF SAID VESSEL WHILE THE LATTER IS ROTATING; MEANS FOR APPLYING HEAT TO THE SLURRY WITHIN SAID VESSEL WHILE THE LATTER IS ROTATING; AND MEANS CONSTRUCTED AND ARRANGED TO DISCHARGE HOT SLURRY FROM THE OTHER END OF SAID VESSEL WHILE THE LATTER IS ROTATED BY SAID MECHANISM, SUCH DISCHARGING MEANS COMPRISING A PIPE ROTATABLE WITH SAID VESSEL AND LOCATED WITHIN SAID VESSEL ADJACENT THE OTHER END THEREOF, SAID PIPE HAVING ITS INLET END LOCATED ADJACENT THE INNER CYLINDRICAL SURFACE OF SAID VESSEL AND EXTENDING IN THE DIRECTION OF ROTATION OF SAID VESSEL SO AS TO SCOOP HOT SLURRY INTO SAID PIPE AS SAID VESSEL ROTATES, SAID PIPE HAVING ITS OUTLET LOCATED AT THE LONGITUDINAL AXIS OF SAID VESSEL. 